November 25, 2021

Atmospheric River Update

The first of three plumes of moisture (atmospheric rivers) is upon us and moderate rain is currently observed along the coast (see radar at 8:30 AM).  If you are living in the interior of western Washington, NOW is the time to head out for some Thanksgiving exercise.  Rain will move in later this afternoon.  If you are in Oregon, you have the whole day.

This first plume of moisture is associated with the first "atmospheric river" in a sequence of three. You can see the "river" in the satellite-based atmospheric water vapor image shown below. Lots of water vapor over the tropics, with thin tendrils of moisture heading into the midlatitudes, including one approaching our region. As I have explained previously, when such moisture is forced upwards by our terrain, moderate to heavy rain results.

The media has recently discovered this term (atmospheric river), often hinting (or stating) that they are deadly or unusual.    

Let me clarify things.  Atmospheric rivers are normal features of the earth's atmosphere that have been known for a very long time, but were previously called other names (such as the warm sector jet or water sector moisture plume).   The image above has six atmospheric rivers, and a similar image over the Atlantic (below) shows two.
Like anything else, atmospheric rivers vary in strength, location, and longevity.  And if even a modest one gets stuck over a region for a period of time, unusually heavy precipitation totals can occur (such as happened earlier this month over Northwest Washington and southwestern British Columbia.

Let's examine the latest forecasts for our region.  The predicted accumulated precipitation over the 24-h ending 4 AM Friday....the total of the first atmospheric river...... is shown below.

The moisture is coming in from the southwest, so the western slopes of the Olympics, Cascades, and Vancouver Island mountains get quite wet, with totals reaching 2-3 inches.  But Puget Sound and Portland are rain shadowed, generally getting less than an inch.   But if you really want to be dry, head to the lower eastern slopes of the Cascades, where the descending flow will prevent any rain.  

Yes, you can stroll around Vantage or Yakima without a worry about getting wet.

A closer view reveals the profound rainshadow to the northeast of the Olympics.   Wow.  A spot south of Port Townsend should be essentially dry for the period.  No wonder so many folks retire there.  Palm Springs in western Washington.

Friday afternoon and Saturday morning should be dry over the region.  An opportunity to work off some of Thanksgiving excesses.

The next front/atmospheric river will spread precipitation over the region Saturday night and Sunday.  

To illustrate, here is the 24-h precipitation ending 4 PM Sunday.   More precipitation than the Thanksgiving storm, with 5-8 inches at some mountain locations.   But again, profound rain shadowing, particularly over Yakima and Portland.   And unfortunately, little precipitation in California where is it acutely needed.

What about the real rivers?

Below is the latest flooding forecast from the NOAA/NWS river forecast center.  The biggest predicted problem will be the Skagit River, where a moderate flood is predicted, with a minor flood on the Nooksack.

To give you more insight into the situation, below is the river stage level and discharge rate at the Skagit River near Mt. Vernon.  Time is on the x-axis and the current time is shown by the vertical line.  You will notice three peaks in the river level, the first on Saturday from today's atmospheric river and then a larger peak on Monday from the weekend event.   The red horizontal line shows the major flood level..which is barely reached.   We are not going to be close to the November13-16th event, which is also evident in the plot 

The same is true of the Nooksack River, which caused so much trouble recently.  The second event will bring things up to a major flood level, but not nearly as high November 16-17.  Can be thankful for that.

Enjoy Thanksgiving.  I have to start cooking!

November 23, 2021

THREE Atmospheric Rivers Heading Our Way

Washington State and southern Brtish Columbia have experienced a very wet fall so far, with the atmospheric river of last weekend causing substantial flooding over Northwest Washington and the lower Fraser River Valley.

But mother nature is not done with us...we should not expect weather forbearance, considering that Thanksgiving week is climatologically the wettest, stormiest period of the year.

Meteorological ground zero, so to speak.

And to make the message clear:  not one, not two, but THREE significant atmospheric rivers will affect our region during the next seven days, with southern British Columbia getting the worst of it.

Let me show you the predicted distributions of atmospheric moisture from the UW WRF modeling system.

First, Thursday morning, with a potent atmosphere river of subtropical moisture aimed for northwest Washington State and southern BC.  A wet turkey day.  Sorry.

By Saturday night ANOTHER atmosphere makes landfall in the same place! 

And Tuesday afternoon an EVEN STRONGER atmospheric river takes aims on southern British Columbia.

How much rain is expected?  I will show you the accumulated totals through three times during the next week....and don't continue if you are meteorologically squeamish.

Through 4 PM Thrusday  there is up to five inches in the mountains of southwest BC and northwest Washington.  Puget Sound will get wet, but somewhat rain shadowed by the Olympics.

The total through 4 PM Saturday is more serious, with totals approaching 10 inches over the windward slopes of the mountains of Vancouver Island and the northern extension of the Cascades.

And by 4 PM Tuesday, things are getting serious with more than 10 inches over extensive areas of southwestern BC.  There is going to be flooding.  One good thing:  it appears that the North Cascades and Fraser River Valley will be out of the central plume of moisture--but wet enough.

And I have some soggy news to tell you about the future.  The latest extended forecast of the European Center through January 7 projects wetter than normal conditions (see below).  Sorry.  Of concern is the lack of precipitation in California... they acutely need it.

November 21, 2021

Were the Sumas Floods Caused by Global Warming? The Evidence Says No.

Last weekend there were highly damaging floods over Northwest Washington, with the town of Sumas and its vicinity being inundated by floodwaters.  Several landslides occurred, including some that closed  I5 near Bellingham.

Town of Sumas, 2021, WSDOT Photo

Within hours of this heavy rainfall event, politicians and the media were suggesting that this event was somehow unique and the result of global warming.

For example, Governor Inslee called the flooding an example of “a permanent state of attack by the forces of climate change.”   The New York Times claimed that flooding in Northwest Washington was caused by climate change (see below)

Similar claims were found in the Washington Post and the Guardian.  And, of course, the Seattle Times had several stories, supported by a slew of "experts" (such as a Simon Fraser Professor) stating that climate change contributed to the flooding.  

The truth is very different than these claims.   The Sumas area is extraordinarily prone to flooding and has experienced flooding many times before.   And as I will demonstrate below, there is no evidence whatsoever that global warming caused the heavy rainfall associated with this event.

A Flood-Prone Region

The town of Sumas is within the historical flood plain of the Fraser River, with an additional flooding threat from local rivers such as the Nooksack (see maps below from a 2005 report by Dr. Jacek Scibek and Dr. Diana Allen of Simon Fraser University)

Importantly there was a large historic lake near Sumas and Abbotsford (Sumas Lake) that was drained for use in agriculture.   In short, a low-lying, historically wet area that has always been prone to flooding.

Previous Flooding

Flooding is not a new visitor to the Sumas area, which has experienced flooding many times during the past century.   The streets of Sumas was similarly flooded in February 2020 (see below)

And there were many previous major floods, including those in 1990 and 1951, to name only a few (see some more examples from the Whatcom County analysis of flooding events).  You build a town in a historical river delta in one of the wettest portions of North American, you can expect trouble.

To say that flooding in Sumas or the region is something new, unprecedented, or unique is simply not correct.  Those making such claims should have spent a little time examining historical floods of the region..

Global Warming And Heavy Precipitation

There has been a LOT of handwaving about the heavy precipitation during this event, claiming it was the result of global warming.  Or that it was greatly enhanced by global warming.

Yes, we had a major rainfall event, but to make a claim that global warming was the origin, it is necessary to demonstrate that there has been a progressive increase in heavy rain, something that would be a sign of a global warming origin.

Let's look at the data.  Karin Bumbaco, Associate Washington State Climatologist, graciously provided me with plots of annual maximum 24-h rainfall at Bellingham, WA, and at the nearby Clearbrook official climatological observing site, with the latter having a very long record (see below).  

There is NO HINT of a trend towards more extreme precipitation at either of these sites.  According to Karin, the big peak in the mid-1930s was from an error in putting two days of rainfall into one day.

Such a lack of evidence of global warming is consistent with state-of-science regional climate modeling, which found that climate models (driven by very aggressive increases in greenhouse gas emissions (RCP8.5) did not produce significant increases in 24-h maximum precipitation in the area over the past half-century (results for Bellingham is shown below). By the END of the century (not shown here), aggressive global warming will increase the heaviest precipitation...but that is in the future.

But wait! There is even more evidence against a global warming contribution to this localized heavy precipitation event.

The origin of this event was a moderate atmospheric river, in which a narrow plume of water vapor was forced upward by our local mountains (see plot of water vapor at 4 PM last Sunday).

If global warming was important, then one would look for above-normal sea surface temperatures along the atmospheric river's path, which would provide additional moisture to the air.  

Below are the sea surface temperature anomalies (differences from normal) for the period leading up and including the atmospheric river in question.  It was cooler than normal immediately off our coast and near normal for virtually the entire path of the atmospheric river. With La Nina conditions, the water temperatures near the equator were BELOW normal.  No sign of a global warming contribution.

Forest Fires Did Not Contribute to the Flooding

In desperation, some of the global warming advocates are suggesting, without a shred of evidence, that the forest fires from last summer were contributing to the flooding.  Specifically, they claim that debris from the fires and less absorptive capacity of the burned landscapes resulted in more water and material entering the rivers.   

We can see how much of the land immediately around the flooding areas was burnt using NASA MODIS imagery (see below for October 31st, when it was clear).   Recently burned landscapes have a reddish hue  (I have indicated an example of a recent fire, east of the Cascade crest, with a red arrow.

It is obvious that there are no major burnt areas around the flooding area or the associated river basins that received heavy precipitation during this event.  So wildfire burnt areas did not make a contribution to these fires.


Another claim, as found in the New York Times, was that there was low snowpack (due to global warming) before the flood, leading to a reduced capacity to soak up the rainwater.  But that was not true:  the snowpack was well above normal prior to the event (USDA Snotel map a few days before the flood is shown below).   The snowpack was well above normal.....not exactly the kind of situation associated with global warming.  I mean MUCH above normal.

I should note that melting snow probably had little impact on this flooding event.  There are several papers (such as this one) that documents that rain on snow melting is very small compared to the rainfall itself.   Furthermore, there was little low-elevation snow before this event, which would be the most likely to contribute.


It is both concerning and problematic that some local politicians, local and national media, and even some scientists are willing to stretch the truth about the origins of this serious flooding event, suggesting a major contribution from global warming (frequently called "climate change".  

Society can not effectively deal with environmental threats when it is provided with hyped or false information.  And providing such false information, even in the hope of motivating people to "do the right thing",  has substantial ethical problems.

November 19, 2021

Dry Weekend and the Roadway Icing Threat: All in My New Podcast

The coming weekend will be unusual for the region:  it will be totally dry as high pressure builds over the region!

Sunday at 4 PM.  500 hPa heights (like pressure at 18,000 ft)

This dry period is particularly welcome, allowing Northwest Washington a period to dry out before more rain comes in next week.

But high pressure during fall can cause problems, allowing the surface to cool off to below freezing and allowing the possibility of roadway icing.

My podcast describes this threat and how you can be on the lookout for potential signs of ice formation.

You can listen to the podcast below or through your favorite podcast server.

Some major podcast servers:

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My next blog will be on the Sumas/NW Washington flooding, examining whether global warming is the cause, as claimed by some media and politicians.

November 18, 2021

Shocking Cloud Pattern: Random Chance, An Unknown Phenomenon, or the Work of the Devil?

 Today I have gotten several emails from folks seeing an unusual, if not disturbing, cloud pattern in the visible satellite imagery.

I mean odd.

As shown below, you can see the object of concern.....a nearly perfect rectangle in the low clouds (mainly stratus and stratocumulus) due west of Baja California

Here is a closer view.   Wow.

What is particularly odd is that the box seems to nearly remain in place over time.  This is not normal.

We have some international experts on low clouds in the subtropics in my department. In the past, several have talked about human intervention to modify such clouds artificially as a tool to reduce global warming.

They assured me that no such experiment was going on and they could not explain this bizarre appearance.

The Guardian newspaper also emailed about it, asking if this feature is the result of global warming.  I assured them that there was no reason to expect that to be the case.  And Charles Mudede, the self-styled "Green Mussolini"  at the Seattle Stranger, also called, suggesting it was a "Wiccan rectangle."   He also noted that it could be related to "Lucifer's rectangle."    

You have to hand it to the Seattle Stranger staff, they are well informed in matters related to the devil and witchcraft.

The truth is that the cloud rectangle is probably just a random natural phenomenon: with enough time a strange geometric pattern is bound to appear.  

But you never know.....

November 15, 2021

Extreme Precipitation and Flooding in Whatcom County

 Extreme flooding forced by extraordinary precipitation has flooded the town of Sumas and other locales in Whatcom County.

Landslides closed I5 and some other roads, and sewage overflows are threatening some water supplies in the area.

The pictures are stunning.

Downtown Sumas was flooded this morning.

The nearby town of Everson is flooded.

And landslides closed I5 near Bellingham:

The Nooksack River achieved its all-time record river stage.

The cause of these terrible conditions is very wet autumn followed by extremely heavy rainfall over the weekend.  Let me show you.

Here are the 72 hr totals ending at 6 PM today.  A number of locations reported 8-10 inches...unbelievable... with 8.94 inches as Sumas Mountain and 9.88 inches near the international border.  Orcas Island, which is closer to the Olympic Rainshadow, got around 5 inches.

But what made this even so deadly is that most of the precipitation fell in a 24-h period on Sunday (midnight to midnight).   This is shown below for the Sumas Mountain observing site.  Around 7 inches in 24 hours.  Wow.

I am happy to report that weather forecast models accurately predicted this torrential rain, something shown by the forecast of accumulated rain made on Friday at 4 AM for the total through 4 AM Monday.  Not bad.   Pretty impressive rainshadow to the NE of the Olympics.

You see the yellow colors....those are the heaviest amounts.

We are going to dry out during the next several days, but the damage has been done.

We are now "enjoying" the wettest autumn on record for many locations in western Washington...but that "honor" should be lost with the dry period ahead.  But the ground is saturated throughout the region, and the WA State DNR's landslide warning system has areas of concern, particularly Whatcom County and along the coast (the other area with lots of rain).


And yes, we had strong winds today with the intense front, with gusts reaching 50-65 miles per hour in places.  Whidbey Island is essentially blacked out, with large outages in the South Sound and elsewhere (see below)

We knew all this was coming..... the big question is how society can learn to use the increasing weather forecasting prowess to protect life and property.

I have said this many times, but it bears repeating: the first line of defense against extreme weather is excellent weather prediction, which should allow us to prevent most loss of life and injury and reduce economic damage. 

Deaths from extreme weather are plummeting around the world and better forecasting is one of the reasons.  You would not know that from what you read in the Seattle Times and many other media sources, which play up extreme weather as an apocalyptic threat to the existence of humanity.


I will be doing a book signing and dinner event at Ivar's Salmon House in Seattle on Wednesday, November 17th (6 PM).  You can come just to purchase a book and get it personalized or you can stay for a special dinner, where I will be giving a weather talk.   More information on the event is found here.  You need to make reservations for the dinner (only 80 spaces available). And information about the new edition of my book is here.

Only about 10 spots are left, so if you want to go, reserve a place soon.

November 14, 2021

The Pacific Northwest is in the Subtropics for a Day

 The air feels different today.

Warm, humid, and with a determined breeze that should be moving a grove of palm trees.

Your skin feels moistened and supple, and temperatures will rise to near 60F in the west and as high as 70F over the Columbia Basin.

Seattle, November 14, 2021?

The Northwest has been transported into the subtropics for a day, the result of an odd meteorological wormhole in meteorological space/time.

This blog will explain.

Some of you may demand proof of the tropical origins of our current it is!  

The top figure below shows the trajectories of air over the past five days ending above Tacoma at 500 meters (red), 1000 m (blue), and 2000 m (green).  All three air trajecotires come from south of 30 N west of Baja California.  

The subtropics.  

The bottom  panel shows the heights of the air over the past five days.

The transition occurred last night.

Below are observations of wind, temperature, and moisture (dew point temperature) at the University of Washington.  Early last evening, the winds switched from northeast to south and accelerated greatly, with some gusts to 15-20 meters per second (around 38 mph!). Temperature and dew point (a measure of moisture) surged upward to around 14 C (roughy 57F)


In the map below, the temperatures (black numbers)  this morning at 7 AM show upper 50s over the lowlands of western Washington to the low to mid 60s around the Tri-Cities and Walla Walla. 

The red numbers are gusts and the wind direction shown by the wind barbs:  strong warm southwesterly flow is noted along the coast and descending into eastern Washington, with 25-35 gusts all over the place.

What caused our transition to tropical breezes? 

The passage of an unusually strong warm front last night.

Here is a forecast map for 4 PM yesterday (Saturday).  A strong warm front projected eastward from the low center and was approaching our coast.  The colors show temperatures at around 800m above sea level, going from cool (green) to warm (orange).

While all of you are enjoying your tropical drinks today, consider that mother nature will make us pay for this tropical interlude.

A very strong cold front is approaching and some locations will experience powerful winds.

At  7 AM tomorrow (Monday), a very strong cold front it right off the coast.  The solid lines are isobars, lines of constant sea level pressure), and the front has an intense trough of low pressure associated with it.  Note the large nort-south pressure difference over western WA (which means strong winds) and the big contrast in temperatures (colors) associated with the front

By 4 PM Monday, the front has moved into eastern Washington and an intense pressure difference is positioned over the Cascades.

The strong pressure difference with the front will first cause a surge of powerful westerly winds in the Strait of Juan de Fuca and then strong winds, gusting to 60-80 mph, over the eastern slopes of the Cascades.  The wind gust forecast for 7 PM tomorrow is shown below--pretty scary east of the Cascade crest.  Expect some power outages on northern Whidbey Island and over the eastern Cascade slopes.

And behind the front, our temperatures will greatly cool, with temperatures over the western lowlands only climbing to the mid-40s for the rest of the week. Snow will return to the mountains.  And skiers will hope.....


I will be doing a book signing and dinner event at Ivar's Salmon House in Seattle on Wednesday, November 17th (6 PM).  You can come just to purchase a book and get it personalized or you can stay for a special dinner, where I will be giving a weather talk.   More information on the event is found here.  You need to make reservations for the dinner (only 80 spaces available). And information about the new edition of my book is here.

Half the spot are now reserved, so if you want to go, reserve a place soon.

Atmospheric River Update

The first of three plumes of moisture (atmospheric rivers) is upon us and moderate rain is currently observed along the coast (see radar at ...